Much research has been devoted in recent years to the development of quantum transistors. Proposed devices include the Aharonov-Bohm quantum phase transistor, quantum well transistor, quantum-tunneling transistor, and quantum diffraction transistor. It is an object of the present invention to provide a novel form of a MOS transistor based on a quantum interference effect.
A new low dimensional quantum effect (QID) was predicted theoretically and observed experimentally in solids. QID is based on electron de Broglie wave interference due to special geometry of a solid. Quantum interference causes some quantum states inside the solid to become forbidden, as a result of which the Fermi energy level increases. The magnitude of the change in the Fermi level depends on the exact dimensions of the special geometry of the solid. QID has been observed in a range of materials, including semiconductor materials.
Previously, it was known that quantum interference effects appeared because of a series of protrusions on the surface of a material. More recently it has been shown that quantum interference also occurs due to the presence of a single protrusion.
U.S. Pat. Nos. 6,281,514, 6,495,843, and 6,531,703 disclose methods for promoting the passage of electrons at or through a potential barrier comprising providing a potential barrier having a geometrical shape for causing quantum interference of electron de Broglie wave. Also provided is an electron-emitting surface having a series of indents, the depth of which is chosen so that the probability wave of the electron reflected from the bottom of the indent interferes destructively with the probability wave of the electron reflected from the surface. This results in the increase of tunneling through the potential barrier. A further embodiment provides a method for making an electron-emitting surface having a series of indents.
U.S. Pat. No. 6,680,214 and U.S. Patent. App. Pub. No. 2004/0206881 disclose methods for the induction of a suitable band gap and electron emissive properties into a substance, in which the substrate is provided with a surface structure corresponding to the interference of de Broglie waves.
WO99/064642 discloses a method for fabricating nanostructures directly in a material film, preferably a metal film, deposited on a substrate.
WO04/040617 discloses a method that blocks movement of low energy electrons through a thermoelectric material. This is achieved using a filter that is more transparent to high-energy electrons than to low energy ones. Tunnel barrier on the path of the electrons is used as filter. The filter works on the basis of the wave properties of the electrons. The geometry of the tunnel barrier is such that the barrier becomes transparent for electrons having certain de Broglie wavelength. If the geometry of the barrier is such that its transparency wavelength matches the wavelength of high-energy electrons it will be transparent for high-energy electrons and will be blocking low energy ones by means of tunnel barrier.
U.S. Pat. No. 7,074,498 discloses the use of electrodes having a modified shape and a method of etching a patterned indent onto the surface of a modified electrode, which increases the Fermi energy level inside the modified electrode, leading to a decrease in electron work function. The surface configuration of the modified electrode may resemble a corrugated pattern of squared-off, “u”-shaped ridges and valleys or a regular pattern of rectangular “plateaus” or “holes”. The surface configuration comprises a substantially plane slab of a material having on one surface one or more indents of a depth approximately 5 to 20 times the roughness of said surface and a width approximately 5 to 15 times said depth. Typically the depth of the indents is ≧λ/2 and the width of the indents is >>λ wherein λ is the de Broglie wavelength. The thickness of the slab is typically a multiple of the depth, preferably between 5 and 15 times said depth, and in the range 15 to 75 nm.